In my test setup, I have mounted 50 ohm BNC ports to the input and the output of an passive DM EMI filter. I have connected these ports to RTA 4000 with 50 ohms coax cable. I have set the function generator input impedance to 50 ohms.
With a Tee adaptor, the function generator splitted into two signals. One goes to the input of the filter and the other one goes to the channel 1. I have connected the output of the filter to channel two.
Unexpectedly, I am seeing positive gain. How can a passive filter show a positive gain?
The response:
With a Tee adaptor, the function generator splitted into two signals. One goes to the input of the filter and the other one goes to the channel 1. I have connected the output of the filter to channel two.
Unexpectedly, I am seeing positive gain. How can a passive filter show a positive gain?
The response: